The Human Body

Levels of Organization in the Body Cells Tissues Epithelial, connective, muscular, nervous Organs Examples include stomach, liver, heart Organ Systems Examples include digestive and circulatory systems Organization in the Body All vertebrates share the same basic body plan, with tissues and organs functioning in a similar manner. Here, we will focus on the human body, studying form (anatomy) and function (physiology). The two go hand-in-hand and are an extension of one of biology’s central themes, evolution. Animals are made of complex systems of cells, which must be able to perform all of life’s processes and work in a coordinated fashion to maintain a stable internal environment. Early in a human’s development, groups of cells specialize into three fundamental embryonic or germ layers: endoderm, mesoderm, and ectoderm. These embryonic layers differentiate into a number of specialized cells and tissues. Tissues are groups of cells similar in structure and function and may be held together by some sort of matrix. There are four primary groups of tissues: epithelial, connective, muscular, and nervous. Different tissues functioning together for a common purpose are called organs (eg, stomach, kidney, lung, heart). Organ systems are composed of individual organs working together to accomplish a coordinated activity. For example, the stomach, small intestine and large intestine all play a role in digestion. References Campbell, N. E., & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings. Raven, P. H., & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill.

Tissues in the Human Body Epithelial Covering or lining tissue Connective Joins, stores and supports Muscle Internal and external movement Nerve Conducts electrical signals Blood Muscle Tissues in the Human Body Tissues are groups of cells similar in structure and function. The four primary categories of tissues are epithelial, connective, muscular, and nervous. Epithelial tissues cover the outer and inner surfaces of the body, serving as “gatekeepers” for the passage of materials. Epithelial cells have glandular roles, secreting substances such as mucous and hormones. Some simple epithelial tissues consist of only one layer, while stratified epithelial tissues are comprised of multiple layers. The shape of the cell on the outer surface (columnar, cuboidal, or squamous) facilitates identification of epithelial tissues. Connective tissues help to bind, support, and join other tissues. The cells of connective tissues are sparsely arranged in a profuse extracellular matrix which can be fluid (as in blood), flexible (as in cartilage) or hard and crystalline (as in bone). Muscle tissues, composed of cells called fibers, are unique in the abundance and arrangement of actin and myosin filaments, which enable muscle to contract. In humans, there are three types of muscle tissues: smooth, cardiac, and skeletal. Nerve tissues are comprised primarily of neurons (nerve cells), which detect stimuli and send responses in the form of electrochemical charges called impulses. Nerve tissues include a variety of supporting cells called neuralgia and Schwann cells. These cells support, insulate, and eliminate foreign materials in and around neurons. References Campbell, N. E., & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings. Raven, P. H., & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill. Image Reference LifeART. (1998). Super Anatomy Collection 1-9. Baltimore, MD: Williams & Wilkins, All rights reserved. Nerve

Human Organ Systems Skeletal Muscular Circulatory Immune Respiratory Digestive Excretory Reproductive Nervous Endocrine Integumentary Human Organ Systems Groups of organs working together to perform major activities of the body are called organ systems. The skeletal system, made of bones, cartilage and joints, is the framework of the body. It protects internal organs, stores minerals and provides a place for muscles to attach. The human muscular system is composed of smooth, cardiac and skeletal muscle tissue. Skeletal muscle, attached to the skeleton with dense strips of connective tissue called tendons, is responsible for the movement of body parts. Smooth muscle, sometimes called visceral muscle, is found in internal organs (eg, lines the walls of many blood vessels, makes up the iris of the eye and forms the wall of the gut). Cardiac muscle forms the bulk of the heart which controls blood circulation. The circulatory system—blood, blood vessels and the heart—is the body’s transportation system, moving oxygen, carbon dioxide, nutrients, wastes, hormones, vitamins, minerals and water throughout the body. It also aids in regulation of temperature. The digestive system converts foods to simple substances that can be absorbed and used by the cells of the body. It is composed of the mouth, pharynx, esophagus, stomach, small intestine and large intestine and is aided by several accessory organs (liver, gall bladder, and pancreas). Made up of the skin, lungs, sweat glands and the kidneys, the excretory system removes metabolic wastes from the body. The kidneys are responsible for eliminating the bulk of wastes from the human body. The reproductive system generates reproductive cells (gametes) and provides a mechanism for them to be fertilized and maintained until the developing embryo can survive outside the body. The primary reproductive organs are the ovaries (female) and the testes (male). The nervous system regulates and coordinates the body’s responses to changes in the internal and external environment. Major structures of the nervous system are the brain, spinal cord and nerves. The endocrine system consists of the hypothalamus, pituitary, thyroid, parathyroid and adrenal glands, as well as the pancreas, ovaries and testes. This system helps to maintain homeostasis, regulate temperature, and control growth, development, metabolism and reproduction by secreting and releasing hormones. The first line of defense in protecting the body is the integumentary system, which is composed of the skin, hair, nails, sweat and oil glands. It protects against injury, infection and fluid loss and also aids in temperature regulation. References Campbell, N. E., & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings. Raven, P. H., & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill.

Human Skeletal System Functions Axial and appendicular skeleton Framework and support Protection Storage Axial and appendicular skeleton Bone structure Joints and ligaments Human Skeletal System The skeleton forms a sturdy internal framework of 206 bones and associated tissues – cartilage, tendons, and ligaments. Bones provide the base to which muscles attach and also the leverage required to accomplish external movement. The skeleton protects vital organs such as the brain, spinal cord, heart and lungs. As a living, dynamic tissue, bone stores vitamins and minerals (especially calcium and phosphorus) and houses red bone marrow, which produces blood cells. Anatomists divide the skeleton into two parts, axial and appendicular. The axial skeleton (upright, or core of the body) includes the skull, ribs, sternum and vertebral column. Comprised of the shoulders, arms, hips and legs, the appendicular skeleton forms the appendages that attach to the axial skeleton. Approximately four times as strong as concrete, bone is one of the strongest materials produced by nature. It is a connective tissue composed of cells called osteocytes, which are embedded in a hard, calcified matrix. Bones are made of a dense outer layer of compact material that surrounds a core of loosely structured spongy bone. The compact layer of bone is covered by a fibrous membrane called the periosteum. Cavities within each bone contain red bone marrow (blood-forming tissue) or yellow bone marrow (fat storage). Movement of the skeleton occurs at the joints where two or more bones meet. There are three categories of joints. Slightly movable joints allow some movement but function mainly as a cushion (eg, joints between the vertebra). Freely movable, or synovial, joints allow a range of movement determined by the structure of the joint. Examples of movable joints are the ball and socket (shoulder), hinge (elbow), pivot (between radius, ulna and humerus), and saddle joint (thumb). A few joints found in the skull are non-movable (sutures). Ligaments are inelastic connective tissues which hold bones together in a joint. References Campbell, N. E., & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings. Raven, P. H., & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill. Image Reference LifeART. (1998). Super Anatomy Collection 1-9. Baltimore, MD: Williams & Wilkins, All rights reserved.

Human Skeleton Diagram Sternum Skull Clavicle Ribs Pelvis Femur Patella Tibia Scapula Humerus Ulna Radius Carpals Metacarpals Fibula Tarsals Metatarsals Phalanges Diagram of Human Skeleton The skeleton’s most important function is to provide support for the body. The skull, ribs, sternum and vertebral column make up the “upright,” rigid axial skeleton, while the arms, legs, shoulders and hips compose the more movable appendicular portion of the skeleton. The articulation of bones forms joints and provides the skeleton with flexibility, enabling it to be moved as muscles contract, extend and relax. References Clark, J. O. E. (Ed.). (1989). A Visual Guide to the Human Body. Barnes & Noble Books. Raven, P. H., & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill. Image Reference LifeART. (1998). Super Anatomy Collection 1-9. Baltimore, MD: Williams & Wilkins, All rights reserved.

Compact Bone Tissue Haversian system Blood vessels Osteocyte Diagram of Human Bone Nearly two-thirds of bone is made of various salts, primarily compounds containing phosphorus and calcium, which provide rigidity and hardness. Collagen makes up the remainder of the matrix (nonliving portion of bone tissue). New bone is produced by osteoblasts, which secrete collagen. After the calcium phosphate is deposited in the matrix, some of the osteoblasts become trapped in their own secretion and then are called osteocytes (osteo = bone, cyte = cell). Bone is a dynamic tissue and constantly is reorganized by cells called osteoclasts. Severe bone loss is called osteoporosis. Compact bone consists of concentric rings of calcium and other minerals (lamellae) surrounding a haversian canal (containing blood vessels and nerves that support the osteocytes). The circular structure helps to form columns that allow the bone to withstand stress, forming a basic structure of compact bone called a Haversian system. Reference Clark, J. O. E. (Ed.). (1989). A Visual Guide to the Human Body. Barnes & Noble Books. Raven, P. H. & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill. Image References LifeART. (1998). Super Anatomy Collection 1-9. Baltimore, MD: Williams & Wilkins, All rights reserved.

Cranium (skull) Mandible (jaw)

Clavicle (collarbone) Sternum (breastbone) Humerus (upper arm) Rib Vertebra (backbone)

Pelvis Radius (forearm) Ulna Carpals (wrist) Metacarpals (hand) Phalanges (fingers)

Femur (thigh) Patella (knee cap) Tibia (lower leg) Fibula Tarsals (ankle) Metatarsals (foot) Phalanges (toes)

What are the main functions of the skeletal system? Framework and support of body Where muscles attach Protects internal organs Storage of vitamins and minerals (calcium), and bone marrow (produces blood cells) Human Skeletal System The skeleton forms a sturdy internal framework of 206 bones and associated tissues – cartilage, tendons, and ligaments. Bones provide the base to which muscles attach and also the leverage required to accomplish external movement. The skeleton protects vital organs such as the brain, spinal cord, heart and lungs. As a living, dynamic tissue, bone stores vitamins and minerals (especially calcium and phosphorus) and houses red bone marrow, which produces blood cells. Anatomists divide the skeleton into two parts, axial and appendicular. The axial skeleton (upright, or core of the body) includes the skull, ribs, sternum and vertebral column. Comprised of the shoulders, arms, hips and legs, the appendicular skeleton forms the appendages that attach to the axial skeleton. Approximately four times as strong as concrete, bone is one of the strongest materials produced by nature. It is a connective tissue composed of cells called osteocytes, which are embedded in a hard, calcified matrix. Bones are made of a dense outer layer of compact material that surrounds a core of loosely structured spongy bone. The compact layer of bone is covered by a fibrous membrane called the periosteum. Cavities within each bone contain red bone marrow (blood-forming tissue) or yellow bone marrow (fat storage). Movement of the skeleton occurs at the joints where two or more bones meet. There are three categories of joints. Slightly movable joints allow some movement but function mainly as a cushion (eg, joints between the vertebra). Freely movable, or synovial, joints allow a range of movement determined by the structure of the joint. Examples of movable joints are the ball and socket (shoulder), hinge (elbow), pivot (between radius, ulna and humerus), and saddle joint (thumb). A few joints found in the skull are non-movable (sutures). Ligaments are inelastic connective tissues which hold bones together in a joint. References Campbell, N. E., & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings. Raven, P. H., & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill. Image Reference LifeART. (1998). Super Anatomy Collection 1-9. Baltimore, MD: Williams & Wilkins, All rights reserved.

What types of tissues make up the skeletal system? Connective tissue Cartilage made of protein fibers Bone is formed during “ossification” when cartilage hardens

What are bones? A solid network of LIVING cells and protein fibers that are surrounded by deposits of calcium salts.

What is the advantage of spongy bone tissue in the ends of long bones? The ends of the bone is where force is applied Spongy bone adds strength without adding mass

Which cells are produced in red bone marrow? Red blood cells carry oxygen Some white blood cells Killer T cells B cells (produce antibodies) Platelets help with blood clotting

Compact bone (dense bone) Haversian Canal (contains blood vessels) Spongy bone (adds strength without mass) Periosteum (tough layer of connective tissue surrounding bone)

Joints Place where one bone attaches to another Immovable joints (fixed) Example: bones of skull Slightly moveable joints Example: joints between vertebrae Freely moveable joints Examples: Shoulder, Knee, Elbow, Hand

Freely Moveable Joints

Freely Moveable Joints